Stabilized polyaryl ether ketone molding compositions

ABSTRACT

Stabilized polyaryl ether ketone molding compositions containing as essential components 
     A) from 50 to 99.99% by weight of a polyaryl ether ketone prepared by electrophilic polycondensation and composed to an extent of not less than 50 mol % of units of the formula I&#39; ##STR1##  where s and t are each 0, 1, 2 or 3, T and T&#39; are each --0-- or --CO-- and Ar is meta-phenylene, paraphenylene or two aromatic rings linked to each other in the meta or para position by a chemical bond, or the ring-substituted C 1  -C 8  -alkyl, C 6  -C 20  -aryl or halogen derivatives thereof, 
     B) from 0.01 to 4% by weight of at least one organic compound which has a base constant pk b  within the range from 2 to 12 and a boiling point of higher than 300° C., 
     C) from 0 to 50% by weight of a further thermoplastic other than A), and 
     D) from 0 to 45% by weight of fibrous or particulate fillers or mixtures thereof.

The present invention relates to stabilized polyaryl ether ketonemolding compositions containing as essential components

A) from 50 to 99.99% by weight of a polyaryl ether ketone prepared byelectrophilic polycondensation and composed to an extent of not lessthan 50 mol % of units of the formula I' ##STR2## where s and t are each0, 1, 2 or 3, T and T' are each --O-- or --CO-- and Ar ismeta-phenylene, paraphenylene or two aromatic rings linked to each otherin the meta or para position by a chemical bond, or the ring-substitutedC₁ -C₈ -alkyl, C₆ -C₂₀ -aryl or halogen derivatives thereof,

B) from 0.01 to 4% by weight of at least one organic compound which hasa base constant pk_(b) within the range from 2 to 12 and a boiling pointof higher than 300° C.,

C) from 0 to 50% by weight of a further thermoplastic other than A), and

D) from 0 to 45% by weight of fibrous or particulate fillers or mixturesthereof.

The present invention further relates to the use of such stabilizedpolyaryl ether ketone molding compositions for producing fibers, filmsand moldings and to fibers, films and moldings which contain thesepolyaryl ether ketone molding compositions as essential components.

Polyaryl ether ketone molding compositions are high grade thermoplasticswhich are notable for a particularly high heat resistance, hightoughness, very good mechanical properties and resistance to commonsolvents.

Polyaryl ether ketones can be prepared by two different processes knownper se. In the so-called nucleophilic polycondensation process an oxygenlinkage is formed by reacting for example aromatic dihydroxy compoundswith difluoroketones with base catalysis. Such a process is describedfor example in EP-A-1879.

A second way of preparing polyaryl ether ketones is by electrophilic(Friedel-Crafts) polycondensation. It involves forming the carbonyllinkage either by reacting an aromatic dicarbonyl dichloride or phosgenewith an aromatic containing two hydrogen atoms which are replaceable byelectrophilic substitution, or polycondensing an aromatic carbonylchloride containing not only an acid chloride group but also areplaceable hydrogen atom with itself.

Friedel-Crafts reactions are customarily carried out in the presence ofa Lewis acid as catalyst in solution, as described for example in U.S.Pat. Nos. 3,441,538, 3,442,857, 3,953,400, DE-A-3,241,444, DE-A-34 16445 and DE-A-34 16 446. Reaction in the presence of a Lewis acid and aLewis base is likewise possible and is described for example in EP-A-124276.

The polyether ketones prepared by electrophilic polycondensation can besubstantially decontaminated of the acids present by extraction with asuitable solvent, but traces of acid will remain behind in the polymer.

When polyaryl ether ketone molding compositions are processed in themelt, temperatures of 400° C., preferably even 450° C., are reached. Atthese very high temperatures even small traces of acid can damage thepolymer. For this reason it was proposed in DE-A-24 19 044 thatamphoteric metal oxides be added to the polymer. Owing to their basicproperties, they are capable of binding or neutralizing the trace acid.EP-A-197 727 proposes using molecular sieves for the same purpose.However, these stabilizers both have the disadvantage that they do notbecome homogeneously dispersed in the polymer and may even aggregatetogether to form large particles. In the manufacture of very fine fibersor films, therefore, these additives can lead to considerable processingproblems. Being infusible substances, they may in addition have aneffect on the crystallization characteristics of partly crystallinepolymers. Moreover, the metal oxides and molecular sieves in questiongradually tend to absorb water which is not given off again at thedrying temperatures customary for polymers. But at the significantlyhigher processing temperatures water may then be released and causefoaming of the polymer.

It is an object of the present invention to remedy the aforementioneddefects.

We have found that this object is achieved by the stabilized polyarylether ketone molding compositions defined at the beginning. We have alsofound them to be useful for producing fibers, films and moldings.

The polyaryl ether ketones utilized as component

A) are at least 50 mol % units of the formula I' ##STR3## where s and tare each 0, 1, 2 or 3, T and T' are each oxygen or carbonyl and Ar ismeta-phenylene, paraphenylene or two aromatic rings linked to each otherin the meta or para position by a chemical bond and in particular is4,4'-biphenylene. In principle, the aromatic units of the polyaryl etherketones I' can be substituted by C₁ -C₈ -alkyl, C₆ -C₂₀ -aryl orhalogen. In general, however, the unsubstituted derivatives arepreferred.

Units of the formula I ##STR4## should be mentioned in particular.Examples of particularly preferred units of the formula I are: ##STR5##and in particular ##STR6##

In terms of the substituents T and T' and the parameters s and t theforegoing examples may be described as follows:

    ______________________________________                                                 S   t           T      T'                                            ______________________________________                                        Ia         0     0           --   --                                          Ib         1     0           0    --                                          Ic         0     1           --   CO                                          Id         1     0           CO   --                                          Ie         1     1           CO   CO                                          ______________________________________                                    

Component A) is used in amounts of from 50 to 99.99% by weight, based onthe total weight of the molding composition, preferably from 60 to99.99% by weight, in particular from 70 to 99.99% by weight.

The polyaryl ether ketones are prepared by electrophilicpolycondensation; the customary conditions known to those skilled in theart are employed. If the starting materials used are aromatic dicarbonyldichlorides and aromatics with two replaceable hydrogen atoms, suitablepossibilities are for example terephthaloyl dichloride,4,4'-biphenyldicarbonyl dichloride, diphenyl ether, 1,4-diphenoxybenzeneand 4,4'-diphenoxybenzophenone. An example of a self-condensable monomeris 4-phenoxybenzoyl chloride.

The component B) used as a stabilizer has a base constant pk_(b) of from2 to 12, preferably from 3 to 11, and a boiling point of higher than300° C., preferably within the range from 320° to 500° C. Examples ofsuitable compounds are 2,3-bipyridine, 4-benzoylpyridine,2,6-diphenylpyridine, 2,6-bis(benzoylphenyl)pyridine,2,6-bis(4-benzoylphenoxy)pyridine, 2,2',6,2"-terpyridine, phenazine,3,4-benzoquinoline, 7,8-benzoquinoline, 2-phenylquinoline,2-phenylindole, 1-methyl-2-phenylindole, 1,2-diphenylindole,9-phenylcarbazole, dibenzothiophene and thioxanthone, of which4-benzoylpyridine, 9-phenylcarbazole and 2-phenylindole are preferred.Mixtures of these compounds may also be used.

Component B) is used in amounts of from 0.01 to 4% by weight, preferablyfrom 0.1 to 1% by weight.

In addition, further thermoplastics C) which are different from A) canbe mixed in. Suitable for this purpose are in particular polyaryl ethersulfones and copolymers thereof, polyether imides, polyamide imides,polyimides, aromatic polyesters, polyphenylene sulfides, fluoropolymersand aliphatic or aromatic polyamides.

Appropriate products would be known to those skilled in the art and arecommercially available.

These polymers may be added in amounts of from 0 to 50% by weight,preferably from 5 to 30% by weight.

In addition the stabilized polyaryl ether ketone molding compositionsaccording to the present invention may contain as component D) fibrousor particulate fillers and also mixtures thereof in amounts of from 0 to45% by weight, in particular from 5 to 40% by weight. Suitablereinforcing fillers are for example asbestos or fibers of aramid, glassor carbon, which may be used not only as short fibers but also asendless fibers. It is also possible to admix pigments such as titaniumdioxide, cadmium sulfite, zinc sulfite, barium sulfate and carbon black.Other suitable additives and auxiliaries are for example flameretardants, further stabilizers other than B), and customary processingaids.

To prepare the stabilized polyaryl ether ketone molding compositionsaccording to the present invention, components A) and B) and, if used,C) and D) can be reacted in a mixing apparatus, preferably in anextruder, at a housing temperature of from 350° to 450° C., preferablyfrom 390° to 420° C. Component B) is stable to customary mixingconditions and residence times. Preferably, the extrudate is in the formof a strand which is granulated.

The stabilized polyaryl ether ketone molding compositions according tothe present invention are significantly more stable in the melt thannonstabilized molding compositions. The stabilizers described formhomogeneous solutions in the polymers, do not tend to aggregate andtherefore do not cause any processing problems in the manufacture ofvery fine fibers or films. The stabilized polyaryl ether ketone moldingcompositions are therefore suitable in particular for manufacturingfibers, films and moldings.

EXAMPLES Preparation of Polyaryl Ether Ketone

The method described in Example 13 of EP-A-124 276 was used to prepare apolyaryl ether ketone of structure Ie ##STR7## having an inherentviscosity of 0.997 (measured in a solution of 0.5 g/100 ml ofconcentrated sulfuric acid at 25° C.).

EXAMPLES 1 to 5 Preparation of Stabilized Polyaryl Ether Ketone MoldingCompositions

The polyaryl ether ketone was in each case intensively mixed with 0.5%by weight of stabilizer, and the mixture was extruded from an extruderat a housing temperature of 400° C. in strand form and granulated.

COMPARATIVE EXAMPLES CE1 TO CE3

CE1: The polyaryl ether ketone was extruded and granulated as inExamples 1 to 5 without addition of a stabilizer.

CE2: The procedure was the same as in Examples 1 to 5, except that 0.5%by weight of commercial basic molecular sieve was incorporated.

CE3: The procedure was the same as in Examples 1 to 5, except that 0.5%by weight of a basic aluminum oxide was incorporated.

Each granular product obtained was tested for melt stability. The testtook the form of a determination of the melt volume index (MVI) by themethod designated DIN 53 735-MFI-B using a type MP-D instrument fromGottfert at 400° C. under a load of 10 kg. Each sample was subjected tothree measurements following a heating-up time of 5, 30 and 60 minutes.The results of the melt flow index measurements are summarized in thetable.

                  TABLE                                                           ______________________________________                                                        MVI [ccm/10 min]                                              Example Stabilizer    5 min    30 min 60 min                                  ______________________________________                                        1       4-benzoylpyridine                                                                           55.2     53.9   48.3                                    2       7,8-benzoquinoline                                                                          57.6     46.8   38.9                                    3       9-phenylcarbazole                                                                           59.5     59.6   46.8                                    4       2-phenylindole                                                                              63.9     59.7   46.4                                    5       1-methyl-2-phenyl-                                                                          64.4     62.8   45.3                                            indole                                                                CE1       --          51.8     42.8   32.1                                    CE2*    Molecular sieve                                                                             60.3     56.3   45.1                                            (basic)                                                               CE3*    Aluminum oxide                                                                              49.7     48.8   46.1                                            (basic)                                                               ______________________________________                                         *When trying to produce fibers from the polymer by melt spinning, a solid     material was found to build up at the spinneret plate, causing filament       breakage from time to time. After about 1 hour a melt filter installed in     the melt duct had become blinded.                                        

We claim:
 1. A stabilized polyaryl ether ketone molding compositioncontaining as essential componentsA) from 50 to 99.99% by weight of aLewis acid containing polyaryl ether ketone prepared by electrophilicpolycondensation and composed to an extent of not less than 50 mol % ofunits for the formula I' ##STR8## where s and t are each 0, 1, 2 or 3, Tand T' are each --O-- or --CO-- and Ar is meta-phenylene, paraphenyleneor two aromatic rings linked to each other in the meta or para positionby a chemical bond, or the ring-substituted C₁ -C₈ -alkyl, C₆ -C₂₀ -arylor halogen derivatives thereof, B) from 0.01 to 4% by weight of at leastone organic compound which has a base constant pk_(b) within the rangefrom 2 to 12 and a boiling point of higher than 300° C., C) from 0 to50% by weight of a further thermoplastic other than A), and D) from 0 to45% by weight of fibrous or particulate fillers or mixtures thereof. 2.A stabilized polyaryl ether ketone molding composition as claimed inclaim 1, in which component A) comprises a polyaryl ether ketone of aunit I ##STR9##
 3. A stabilized polyaryl ether ketone moldingcomposition as claimed in claim 1, containing component B) in an amountof from 0.1 to 1% by weight.
 4. A stabilized polyaryl ether ketonemolding composition as claimed in claim 1, wherein component B) isselected from the group consisting of 2,3-bipyridine, 4-benzoylpyridine,2,6-diphenylpyridine, 2,6-bis(benzoylphenyl)pyridine,2,6-bis(4-benzoylphenoxy)pyridine, 2,2',6,2"-terpyridine, phenazine,3,4-benzoquinoline, 7,8-benzoquinoline, 2-phenylquinoline,2-phenylindole, 1-methyl-2-phenylindole, 1,2-diphenylindole,9-phenylcarbazole, dibenzothiophene, thioxanthone and mixtures thereof.5. A stabilized polyaryl ether ketone molding composition as claimed inclaim 1, wherein component A) comprises a polyaryl ether ketone of aunit Ie ##STR10##
 6. A fiber, film or molding obtainable from thestabilized polyaryl ether ketone molding composition as claimed in claim1 as an essential component.
 7. A process for stabilizing a polyarylether ketone molding composition containing as essential componentsA)from 50 to 99.99% by weight of an acid containing polyaryl ether ketoneprepared by electrophilic polycondensation and composed to an extent ofnot less than 50 mol % of units for the formula I' ##STR11## where s andt are each 0, 1, 2 or 3, T and T' are each --O-- or --CO-- and Ar ismeta-phenylene, paraphenylene or two aromatic rings linked to each otherin the meta or para position by a chemical bond, or the ring-substitutedC₁ -C₈ -alkyl, C₆ -C₂₀ -aryl or halogen derivatives thereof, B) from 0to 50% by weight of a further thermoplastic other than A), and C) from 0to 45% by weight of fibrous or particulate fillers or mixturesthereof,comprising neutralizing the acid by adding during theextrudation from 0.01 to 4% by weight of at least one organic compoundwhich has a base constant pk_(b) within the range from 2 to 12 and aboiling point of higher than 300° C.